This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
using namespace std;
vector<pair<int,int> >v[30005];
int bruh[2005][2005];
main(){
  cin.tie(0);
  ios::sync_with_stdio(0);
	int N,M;
	cin>>N>>M;
	vector<pair<int,int> >hi;
	for(int i=0;i<M;i++){
		int a,b;
		cin>>a>>b;
		hi.push_back(make_pair(a,b));
	}
	for(int i=0;i<N+3;i++){
		for(int j=0;j<N+3;j++) bruh[i][j] = 1e9;
	}
	for(int i=0;i<M;i++){
		int x = 1;
		while(hi[i].first-x*hi[i].second>=0){
			v[hi[i].first].push_back(make_pair(hi[i].first-x*hi[i].second,x));
			x++;
		}
		x = 1;
		while(hi[i].first+x*hi[i].second<N){
			v[hi[i].first].push_back(make_pair(hi[i].first+x*hi[i].second,x));
			x++;
		}
	}
	priority_queue<pair<int,int>,vector<pair<int,int> >, greater<pair<int,int> >  >pq;
	pq.push(make_pair(0,hi[0].first));
	int dist[30005];
	for(int i=0;i<30004;i++) dist[i] = 1e9;
	dist[hi[0].first] = 0;
	while(!pq.empty()){
		int dis = pq.top().first;
		int no = pq.top().second;
		pq.pop();
		if(dist[no]<dis)continue;
		for(pair<int,int>p:v[no]){
			if(dis+p.second<dist[p.first]){
				dist[p.first] = dis+p.second;
				pq.push(make_pair(dis+p.second,p.first));
			}
		}
	}
	if(dist[hi[1].first] == 1e9) cout<<"-1";
	else cout<<dist[hi[1].first];
}
Compilation message (stderr)
skyscraper.cpp:5:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    5 | main(){
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